| Abstract: | In order to determine the effects of stellate ganglion stimulation (SGS) on static lung compliance, pressure-volume relationships were measured on lungs in situ in cats anesthetized with ketamine. The lungs were inflated with 100% oxygen to 100, 93.75, 87.5, 81.25, 75, 50, and 25% TLC as determined at 20 cm H2O transpulmonary pressure. After a maximal filling, lungs were inflated twice to each volume, alternating unstimulated and SGS conditions. Static lung compliance was decreased by SGS at 93.75 (5.7 +/- 0.4 (SE) vs. 5.4 +/- 0.4 ml/cm H2O; P less than 0.05) and 87.5% TLC (6)6 +/- 0.6 vs 6.0 +/- 0.5 ml/cm H2O; P less than 0.05). In order to assess possible effects of SGS on surfactant that might be related to the loss of compliance, lung lipids and proteins obtained during SGS were quantitated. Total phospholipid (TPL) increased from 3.22 +/- 0.33 to 4.16 +/- 0.23 mg/g lung after 1 min 7V SGS (P less than 0.05) and to 4.58 +/- 0.61 mg/g lung after 4 min 20V (P less than 0.05). The ratio of cholesterol (chol) to disaturated phosphatidylcholine (DSPC) decreased after 4 and 6 min, and may have resulted in increased surface tension forces at high lung volumes. The data from this study lend support to previous findings which showed that the compliance decrease during SGS may be related to increased surface tension forces. |
